My point was that, putting the SS funds into gov’t bonds was a prudent thing to do when the alternative is to leave the cash idle and earn no interest. Later, they didn’t even use the slight of hand of buying Treasuries...they just put the funds into the revenue pool.
No, the SS surplus always went into Treasuries and that didn’t stop until recently when receipts fell below expenditures.
The idea that the SS funds earned interest only extended the fiction that SS funds were invested. It is like making a loan to yourself and paying interest to yourself. A gimmick.